Fencing means perimeter so that mean 2 times the length + 2 times the width. Kelly has 240 feet of fencing and the width is 20 feet. So 240 = 2 lengths + 2 widths. So we have to multiply the width by 2 and subtract it from 240. 20x2 = 40. Now 240-40 = 200. So we are left with 200 feet of fencing for the length. Since we have to multiply the length by 2 in the perimeter, we can divide 200 by 2 to get the length. 200/2 = 100. So the length of the fence is 100 feet. Hope this helps and if so please leave a good rating and thanks and maybe even brainliest answer. Thank you I really appreciate it. Have a nice day!